U.S. Pat. No. 4,139,922 discusses a carpet cleaning device having self-adjustable brushes carried by a spring mounted stationary shaft intended to provide floating brush action within the frame of the device. The mounting springs push directly onto the ends of the brush shafts. The mounting springs are received within slots in the frame which results in objectionable noise of metal striking metal when bottoming out occurs. There is no disclosure of any independent vertical movement of one end of the brush with respect to the other end as in the present invention and no such action appears to be provided. In any case, this structure does not provide for smooth and consistent vertical sliding action at each end of the brush such as is provided by the device of the present invention. More particularly, U.S. Pat. No. 4,139,922 involves a complex and expensive double sprocket and chain system which is exposed and without shielding or other protection from corrosive cleaning solutions. In addition, the system is exposed to dirt and lint, the accumulation of which can rapidly jam the sprockets and chain drive. The chain drive, being exposed, may convey dirt and liquid to other parts of the unit, creating electrical problems.
U.S. Pat. No. 3,959,848 and U.S. Pat. No. 4,554,702 show disc brushes rotating about and floating up and down along vertical axes within a vacuum cleaner housing.
U.S. Pat. No. 3,802,026 discloses the use of springs to vertically bias an agitator in a dry vacuum cleaning apparatus. The construction permits up and down movement only of the agitator. No means are present in the apparatus to allow independent movement at the ends of the agitator. The apparatus is intended for dry use and it will not operate in a wet condition since slippage of the unprotected centerly located drive belt will occur in the event it becomes wet. Another particular problem with the apparatus is that as the agitator assembly moves up and down, the distance between the pulleys changes, thereby producing resistance to full up and down movement of the agitator, and stretching of the drive belt. The apparatus is also noisy, since the bottoming out of the sliding member causes an objectionable rattling.
U.S. Pat. No. 3,605,172 discloses a variable venture nozzle having two fixed parallel rollers with a channel therebetween to provide a variable channel width. While the irrelevance of this patent is readily apparent, it should be noted that the venture bar will significantly affect the vacuum motor performance, since it will restrict the opening and hence the air flow at the time when it is most needed. Lint collection on the venture bar and associate moving members are prone to fouling.
For many years vacuum cleaners have been provided with a rotatable brush which is intended to contact and brush the surface to be cleaned, to loosen and agitate dirt, grit, debris, etc., so that it can be sucked up into a collection tank or bag by a vacuum motor. The brush is able to perform its intended purpose only to the extent the distal ends of the bristles of the brush are in contact with the surface being cleaned. Keeping the brush in contact is not a problem provided the surface being cleaned is absolutely uniform, smooth and level. However, in many cases, the surface is irregular or bumpy. When this irregular surface condition exists, the efficiency of the brush is diminished, since only some of the bristles can contact the surface being cleaned. Other bristles do not reach the surface and hence are ineffectual in loosening or disturbing the dirt.
Various devices have been proposed in an effort to maintain contact between the brush and the surfaces being cleaned where that surface is irregular. For example, it has been proposed to provide a suspension system for the brush involving a plurality of support arms at each end of the brush, one end of each of the support arms being affixed to the cleaning head assembly and the other end being attached to the brush shaft through some intermediate structures. These proposed suspension systems which include bearings at the joints and motion limiting devices, are complicated and costly to manufacture, have proved to be unreliable in use, and ineffectual in keeping the brush in contact with many types of irregular surfaces.
Another problem with prior art devices has been that they produce irregular tension on the drive belt between the brush and the brush drive motor.
The present invention provides a significant advance in the art of vacuum cleaning apparatus. The brush is carried within the cleaning head assembly using simpler components, which are less costly and easier to manufacture. More importantly, the suspension system employed for the brush according to this invention maintains contact between the brush and the surface being cleaned over virtually any degree or extent of normal surface irregularity. The suspension system automatically adjusts the brush to accommodate irregularities and also to adjust for variations in nap height of rugs.
The present invention also maintains uniform tension in the drive belt between the brush and the brush drive motor over the full range of movement of the brush as it responds to surface irregularities.
It is believed that this invention provides a major improvement in the art and it is to be expected that it will be widely adopted by those skilled in the art.